Optical fiber submarine cables generally comprise a core member carrying the optical fibers (placed in plastic tubes filled with a viscous compound or in helical grooves on the outside of a metal or plastic rod), and an armoring of spirally wound steel wires covered with a tube of ductile, conductive metal (copper or aluminum) welded longitudinally and swaged over the steel wire armoring, and finally, an insulating jacket made of a thermoplastic material such as polyethylene.
Connecting two cable ends of this makeup is difficult, for it is necessary to do all of the following:
fuse or stick together end-to-end the optical fibers in the two cables, while leaving enough slack to avoid fiber breakage from longitudinal stress; PA1 ensure mechanical continuity of the two cables' armorings through the junction by supporting the tensile stress undergone by the cable during its handling; PA1 ensure watertightness of the junction, even under the high pressure conditions of ocean bottoms. PA1 (a) a center section comprising: PA1 (b) a lateral section, on each side of the center section, comprising: PA1 a heat-shrinkable sheath around the junction between the sleeve of the center section and each of the hoods of the lateral sections; PA1 a heat-shrinkable sheath around the junction between the hook of each lateral section and the jacket of the corresponding cable; PA1 the cylindrical section of the tapered cylindrical bore of the anchoring part is fitted with a gasket preventing the penetration of any synthetic resin prior to said resin's hardening; and PA1 at least the inside area of the anchoring parts coming into contact with the steel wires is made of an electrically insulating ceramic material. PA1 (a) the steel wires of the armoring, as well as the swaged copper tube and the outside jacket of the cable ends, are eliminated from the area of the junction over a length notably greater than the length required for said device, exposing the bare optical fibers, PA1 (b) the synthetic resin hoods, the anchoring parts and the metal sleeve are successively engaged over the ends of the optical fiber compartments, PA1 (c) the steel wires of the armoring, the swaged copper tube and the jacket are cut to the length required for the device, PA1 (d) a certain amount of hard-setting synthetic resin filler is introduced in the conical section of the tapered cylindrical bore of the anchoring parts and the ends of the steel armoring wires are flared out inside of said conical section, PA1 (e) the conical steel armoring wire flaring parts are introduced into the anchoring parts; the entire space between the anchoring parts, the ends of the steel wires and the conical flaring parts is filled with synthetic resin filler; then the synthetic resin is made to harden, PA1 (f) the optical fibers required to be joined are fused and their length of slack in relation to the length of the device is wound around the mandrel or tube, PA1 (g) the metal sleeve is pulled back over the center section of the device and screwed onto the two anchoring parts, PA1 (h) the synthetic resin hoods are made to slide up to contact with the metal sleeve.
Up to now, no technique has been proposed to simplify, rationalize and speed junction operations for such cables, despite the inherent slowness of a trial-and-error manual operation and the doubts which it involves with respect to mechanical strength and watertightness of the junction.
The present invention is intended to remedy these inconveniences, and to provide a junction method of assembling it, providing good mechanical strength and good watertightness for the junction, while speeding the jointing of the two cable ends and leaving enough slack in the optical fiber to ensure that the fibers will absorb large variations in length or tension, or a torsional stress.